1SYSTEMD-NOTIFY(1) systemd-notify SYSTEMD-NOTIFY(1)
2
6 systemd-notify - Notify service manager about start-up completion and
7 other daemon status changes
8
10 systemd-notify [OPTIONS...] [VARIABLE=VALUE...]
11 systemd-notify --exec [OPTIONS...] [VARIABLE=VALUE...] ; [CMDLINE...]
13
15 systemd-notify may be called by service scripts to notify the invoking
16 service manager about status changes. It can be used to send arbitrary
17 information, encoded in an environment-block-like list of strings. Most
18 importantly, it can be used for start-up completion notification.
19 This is mostly just a wrapper around sd_notify() and makes this
21 functionality available to shell scripts. For details see sd_notify(3).
22 The command line may carry a list of environment variables to send as
24 part of the status update.
25 Note that systemd will refuse reception of status updates from this
27 command unless NotifyAccess= is appropriately set for the service unit
28 this command is called from. See systemd.service(5) for details.
29 Note that sd_notify() notifications may be attributed to units
31 correctly only if either the sending process is still around at the
32 time the service manager processes the message, or if the sending
33 process is explicitly runtime-tracked by the service manager. The
34 latter is the case if the service manager originally forked off the
35 process, i.e. on all processes that match NotifyAccess=main or
36 NotifyAccess=exec. Conversely, if an auxiliary process of the unit
37 sends an sd_notify() message and immediately exits, the service manager
38 might not be able to properly attribute the message to the unit, and
39 thus will ignore it, even if NotifyAccess=all is set for it. To address
40 this systemd-notify will wait until the notification message has been
41 processed by the service manager. When --no-block is used, this
42 synchronization for reception of notifications is disabled, and hence
43 the aforementioned race may occur if the invoking process is not the
44 service manager or spawned by the service manager.
45 systemd-notify will first attempt to invoke sd_notify() pretending to
47 have the PID of the parent process of systemd-notify (i.e. the invoking
48 process). This will only succeed when invoked with sufficient
49 privileges. On failure, it will then fall back to invoking it under its
50 own PID. This behaviour is useful in order that when the tool is
51 invoked from a shell script the shell process — and not the
52 systemd-notify process — appears as sender of the message, which in
53 turn is helpful if the shell process is the main process of a service,
54 due to the limitations of NotifyAccess=all. Use the --pid= switch to
55 tweak this behaviour.
56
58 The following options are understood:
59 --ready
61 Inform the invoking service manager about service start-up or
62 configuration reload completion. This is equivalent to
63 systemd-notify READY=1. For details about the semantics of this
64 option see sd_notify(3).
65 --reloading
67 Inform the invoking service manager about the beginning of a
68 configuration reload cycle. This is equivalent to systemd-notify
69 RELOADING=1 (but implicitly also sets a MONOTONIC_USEC= field as
70 required for Type=notify-reload services, see systemd.service(5)
71 for details). For details about the semantics of this option see
72 sd_notify(3).
73 --stopping
75 Inform the invoking service manager about the beginning of the
76 shutdown phase of the service. This is equivalent to systemd-notify
77 STOPPING=1. For details about the semantics of this option see
78 sd_notify(3).
79 --pid=
81 Inform the service manager about the main PID of the service. Takes
82 a PID as argument. If the argument is specified as "auto" or
83 omitted, the PID of the process that invoked systemd-notify is
84 used, except if that's the service manager. If the argument is
85 specified as "self", the PID of the systemd-notify command itself
86 is used, and if "parent" is specified the calling process' PID is
87 used — even if it is the service manager. The latter is equivalent
88 to systemd-notify MAINPID=$PID. For details about the semantics of
89 this option see sd_notify(3).
90 If this switch is used in an systemd-notify invocation from a
92 process that shall become the new main process of a service — and
93 which is not the process forked off by the service manager (or the
94 current main process) —, then it is essential to set
95 NotifyAccess=all in the service unit file, or otherwise the
96 notification will be ignored for security reasons. See
97 systemd.service(5) for details.
98 --uid=USER
100 Set the user ID to send the notification from. Takes a UNIX user
101 name or numeric UID. When specified the notification message will
102 be sent with the specified UID as sender, in place of the user the
103 command was invoked as. This option requires sufficient privileges
104 in order to be able manipulate the user identity of the process.
105 --status=
107 Send a free-form human readable status string for the daemon to the
108 service manager. This option takes the status string as argument.
109 This is equivalent to systemd-notify STATUS=.... For details about
110 the semantics of this option see sd_notify(3). This information is
111 shown in systemctl(1)'s status output, among other places.
112 --booted
114 Returns 0 if the system was booted up with systemd, non-zero
115 otherwise. If this option is passed, no message is sent. This
116 option is hence unrelated to the other options. For details about
117 the semantics of this option, see sd_booted(3). An alternate way to
118 check for this state is to call systemctl(1) with the
119 is-system-running command. It will return "offline" if the system
120 was not booted with systemd.
121 --no-block
123 Do not synchronously wait for the requested operation to finish.
124 Use of this option is only recommended when systemd-notify is
125 spawned by the service manager, or when the invoking process is
126 directly spawned by the service manager and has enough privileges
127 to allow systemd-notify to send the notification on its behalf.
128 Sending notifications with this option set is prone to race
129 conditions in all other cases.
130 --exec
132 If specified systemd-notify will execute another command line after
133 it completed its operation, replacing its own process. If used, the
134 list of assignments to include in the message sent must be followed
135 by a ";" character (as separate argument), followed by the command
136 line to execute. This permits "chaining" of commands, i.e. issuing
137 one operation, followed immediately by another, without changing
138 PIDs.
139 Note that many shells interpret ";" as their own separator for
141 command lines, hence when systemd-notify is invoked from a shell
142 the semicolon must usually be escaped as "\;".
143 --fd=
145 Send a file descriptor along with the notification message. This is
146 useful when invoked in services that have the
147 FileDescriptorStoreMax= setting enabled, see systemd.service(5) for
148 details. The specified file descriptor must be passed to
149 systemd-notify when invoked. This option may be used multiple times
150 to pass multiple file descriptors in a single notification message.
151 To use this functionality from a bash shell, use an expression like
153 the following:
154 systemd-notify --fd=4 --fd=5 4</some/file 5</some/other/file
156 --fdname=
158 Set a name to assign to the file descriptors passed via --fd= (see
159 above). This controls the "FDNAME=" field. This setting may only be
160 specified once, and applies to all file descriptors passed. Invoke
161 this tool multiple times in case multiple file descriptors with
162 different file descriptor names shall be submitted.
163 -h, --help
165 Print a short help text and exit.
166 --version
168 Print a short version string and exit.
169
171 On success, 0 is returned, a non-zero failure code otherwise.
172
174 Example 1. Start-up Notification and Status Updates
175 A simple shell daemon that sends start-up notifications after having
177 set up its communication channel. During runtime it sends further
178 status updates to the init system:
179 #!/bin/sh
181 mkfifo /tmp/waldo
183 systemd-notify --ready --status="Waiting for data..."
184 while : ; do
186 read -r a < /tmp/waldo
187 systemd-notify --status="Processing $a"
188 # Do something with $a ...
190 systemd-notify --status="Waiting for data..."
192 done
193
195 systemd(1), systemctl(1), systemd.unit(5), systemd.service(5),
196 sd_notify(3), sd_booted(3)
197systemd 254 SYSTEMD-NOTIFY(1)